Error 324 means QuickBooks can no longer find one of your accounts at your bank, and it's common for this to affect some cards on an American Express account while others keep syncing fine. This usually comes down to which accounts were selected the last time the connection was authorized.
Fix the account showing the error
- Go to All apps, then Accounting, then Bank transactions.
- Find the account showing Error 324 and select Fix now. You'll be taken to Manage connections.
- Select the affected account, then select Disconnect, and confirm. This clears the error and removes the bank feed for that account only.
Reconnect all your American Express accounts together
- Go to All apps, then Accounting, then Bank transactions.
- Select Link account, then search for American Express and sign in with your current credentials.
- When American Express asks which accounts to share, select All Accounts (or Consent All) rather than choosing just one card.
- Select the accounts you want connected in QuickBooks, then complete the setup.
Selecting all accounts during authorization matters here: if only one card gets shared during reconnection, QuickBooks can lose track of the others, and the error effectively moves from one card to the next instead of going away. The bank connection itself typically isn't broken, it's the account selection that needs to include everything at once.
Still receiving the error? Check out this article: Fix bank connection error 324 in QuickBooks Online and Intuit Enterprise Suite, or let us know what steps you tried and we can help you determine where to go next.